This application relates generally to a turbine seal and damper assembly and specifically to a nested seal and damper assembly.
Conventional gas turbine engines include a turbine assembly that has a plurality of turbine blades attached about a circumference of a turbine rotor. Each of the turbine blades is spaced a distance apart from adjacent turbine blades to accommodate movement and expansion during operation. The blades typically include a root that attaches to the rotor, a platform and a blade that extends radially outwardly from the platform.
Problems arise when hot gases penetrate below the platform of the turbine blades. Hot gases flowing over the platform are prevented from leaking between adjacent turbine blades by a seal. This is done because components below the platform are generally not designed to operate for extended durations at the elevated temperatures of the hot gases. The seal is typically a metal sheet nested between adjacent turbine blades on an inner surface of the platform. The seal is typically flexible so as to conform to the inner surface of the platform and prevent the intrusion of hot gases below the platform of the turbine blade. Typically, the seal is disposed against a radially outboard inner surface of the platform of the turbine blade.
In addition to the seal it is common practice to include a damper between adjacent turbine blades to dissipate potentially damaging vibrations. A damper is typically sized to provide sufficient mass and rigidity to dissipate vibration from the turbine blade. Vibrations from the turbine blade are transmitted through frictional contact between the damper and an inner surface of the turbine blade platform. Dampers provide the maximum benefit and dampening when positioned at a radial outermost part of an inner surface of the platform.
Disadvantageously, both the damper and the seal perform to the maximum benefit when positioned against the inner surface of the platform. As appreciated, it is only possible to position either the seal or the damper immediately adjacent the inner surface.
A currently proposed solution provides a single part that performs as both the seal and as the damper. Such a device provides for the desired location of both the damper and the seal. However, the material properties of the seal and the damper are compromised to accommodate the separate functions. That is the seal material is not as flexible as desired in order to provide the dampening properties required and the damper material does not provide the most beneficial dampening properties in order to provide some flexibility for the seal. The compromise between favorable dampening properties and favorable seal properties yields less than desirable performance for both functions.
Accordingly, it is desirable to develop a seal and damper assembly utilizing the most beneficial material for each function while providing the most beneficial placement of the damper and seal.